netdev - Re: [PATCH net-next v4 1/5] netdevsim: maintain a list of probed netdevsims

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Message-ID: <2fa47ece-a8ee-4b16-93f7-801927b9b199@davidwei.uk>
Date: Thu, 21 Dec 2023 16:49:35 -0800
From: David Wei <dw@...idwei.uk>
To: Simon Horman <horms@...nel.org>
Cc: Jakub Kicinski <kuba@...nel.org>, Jiri Pirko <jiri@...nulli.us>,
 Sabrina Dubroca <sd@...asysnail.net>, netdev@...r.kernel.org,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Paolo Abeni <pabeni@...hat.com>
Subject: Re: [PATCH net-next v4 1/5] netdevsim: maintain a list of probed
 netdevsims

On 2023-12-20 08:40, Simon Horman wrote:
> On Tue, Dec 19, 2023 at 05:47:43PM -0800, David Wei wrote:
>> This patch adds a linked list nsim_dev_list of probed netdevsims, added
>> during nsim_drv_probe() and removed during nsim_drv_remove(). A mutex
>> nsim_dev_list_lock protects the list.
>>
>> Signed-off-by: David Wei <dw@...idwei.uk>
>> ---
>>  drivers/net/netdevsim/dev.c       | 17 +++++++++++++++++
>>  drivers/net/netdevsim/netdevsim.h |  1 +
>>  2 files changed, 18 insertions(+)
>>
>> diff --git a/drivers/net/netdevsim/dev.c b/drivers/net/netdevsim/dev.c
>> index b4d3b9cde8bd..e30a12130e07 100644
>> --- a/drivers/net/netdevsim/dev.c
>> +++ b/drivers/net/netdevsim/dev.c
>> @@ -35,6 +35,9 @@
>>  
>>  #include "netdevsim.h"
>>  
>> +static LIST_HEAD(nsim_dev_list);
>> +static DEFINE_MUTEX(nsim_dev_list_lock);
>> +
>>  static unsigned int
>>  nsim_dev_port_index(enum nsim_dev_port_type type, unsigned int port_index)
>>  {
>> @@ -1531,6 +1534,7 @@ int nsim_drv_probe(struct nsim_bus_dev *nsim_bus_dev)
>>  				 nsim_bus_dev->initial_net, &nsim_bus_dev->dev);
>>  	if (!devlink)
>>  		return -ENOMEM;
>> +	mutex_lock(&nsim_dev_list_lock);
>>  	devl_lock(devlink);
>>  	nsim_dev = devlink_priv(devlink);
>>  	nsim_dev->nsim_bus_dev = nsim_bus_dev;
>> @@ -1544,6 +1548,7 @@ int nsim_drv_probe(struct nsim_bus_dev *nsim_bus_dev)
>>  	spin_lock_init(&nsim_dev->fa_cookie_lock);
>>  
>>  	dev_set_drvdata(&nsim_bus_dev->dev, nsim_dev);
>> +	list_add(&nsim_dev->list, &nsim_dev_list);
>>  
>>  	nsim_dev->vfconfigs = kcalloc(nsim_bus_dev->max_vfs,
>>  				      sizeof(struct nsim_vf_config),
>> @@ -1607,6 +1612,7 @@ int nsim_drv_probe(struct nsim_bus_dev *nsim_bus_dev)
>>  
>>  	nsim_dev->esw_mode = DEVLINK_ESWITCH_MODE_LEGACY;
>>  	devl_unlock(devlink);
>> +	mutex_unlock(&nsim_dev_list_lock);
>>  	return 0;
>>  
> 
> Hi David,
> 
> I see Jiri has asked about the scope and type of this lock.
> And updates to address those questions may obviate my observation.
> But it is that mutex_unlock(&nsim_dev_list_lock); needs to
> be added to the unwind ladder:
> 
> 	...
> err_devlink_unlock:
> 	devl_unlock(devlink);
> 	mutex_unlock(&nsim_dev_list_lock);
> 	...
> 
> ...
> 
> Flagged by Smatch.

Hi Simon, thanks for flagging this and I will address it in the next
version.